Previous research by Proffitt et al. (1999, 2003) showed that the perception of spatial layout (geographical slant, egocentric distance) is influenced by altering the observer's bodily state. For example, hills appear steeper and distances appear farther to participants who are fatigued, of old age, or wearing a heavy backpack. Research investigating possible links between emotion and cognition has suggested that emotional state can influence seemingly unrelated aspects of cognition (Gasper and Clore, 2002).

The current study sought to combine these two research programs by asking whether emotion (possibly an aspect of bodily state) can influence the perception of spatial layout. Mood was induced by having participants listen to happy music (major key, upbeat) or sad music (minor key). While listening to the music, participants made three judgments of the slant of the hill: verbal estimate, visual matching, and a visually guided action measure (a haptic palmboard). Sad participants verbally judged the hill as being steeper than those in the happy condition, and the visual matching measure showed a non-significant trend in the same direction. As was found in previous work, the visually guided action measure was unaffected across conditions. Results support the hypothesis that the bodily state associated with a sad mood resembles that of a fatigued or encumbered participant. A similar follow-up study was conducted on the effect of mood on the perception of egocentric distance.